Large buried silos and utility buildings from this period have been found. Chinon was home to a royal monetary workshop in the 7th and 8th centuries; then, from 920 to 954, the Viking threat not having been averted, the Tours workshop was transferred there.
In the 10th century, the fortress was held by the counts of Blois, great vassals of the king of France. The first and most powerful of them, Theobald 1st known as "the cheat" became count around 942 and remained so until 974. Theobald built the first stone tower of the fortress in 954. He surrounded it with its own enclosure that isolates it from the old castrum.